Phosphorus-containing polymers



Patented Mar. 2, 1954 2,671,080 PHOSPHORUS-CON TAININ G POLYMERS William B. McCormac signor to E. I. du P Dany, Wilmington, ware No Drawing. Application August 7,

k, Wilmington, DeL, asnt de Nemours and Com- Del., a corporation of Dela- Serial No. 240,814 14 Claims. (Cl. 260-923) This invention relates to new phosphorus containing interpolymers and to a process for obtaining them.

Most organic polymeric materials deteriorate or decompose at elevated temperatures and are flammable to such an extent that they may not be used in some application for which their properties make them otherwise suitable.

It is an object of this invention to provide polymers which are heat-resistant and which have a high degree of stability against oxidation, reduction and hydrolysis. A further object is to provide polymers which are useful in the fiameproofing of textiles. A still further object is to provide a process for the production of these polymers.

According to this invention, such stable interpolymers are prepared by the reaction of a hydroxyl-containing compound, such as water, an alcohol or a carboxylic acid, with an interpolymer of a polymerizable organic compound containing conjugated olefinic double bonds and a monosubstituted dihalophosphine. By this reaction the dihalotertiaryphosphine groups in the intermediate interpolymer are converted to phosphine oxide groups. The interpolymers containing the dihalotertiaryphosphine group are prepared by reacting together the polymerizable organic compound and the substituted dihalophosphine in the presence of a free radical polymerization catalyst, as described in my copending application Serial No. 240,813.

In a typical and representative embodiment of this inyention, a heat-resistant polymer containing phosphin oxide groups is prepared by first reacting butadiene with dichlorophenylphosphine in the presence of an azonitrile polymerization catalyst to form an interpolymer containing dichlorotertiaryphosphine groups, and thereafter hydrolyzing this product by adding water to the reaction mixture.

The polymerizable compounds containing conjugated olefinic double bonds which are useful in the practice of this invention include hydrocarbons, such as butadiene, isoprene, 2,3-dimethyl-l, B-butadiene, 1,3-pentadiene, 2,4-hexadiene, 2,4-heptadiene, 2,5dimethyl-2,4-hexa diene, myrcene, allo-ocimene, 2,6-dimethyl-l,3- heptadiene, 1,3-decadiene, 2-phenyl-l,3-butadiene, 2,3-dipheny1-1,3-butadiene, 2-benzyl-1,3- butadiene, 1,1'-biscyclohexenyl, 2-tolyl-1,3-butadiene, l-vinyl-l-cyclohexene, 1,2-dimethylenecyclohexane, 1,3,5-hexatriene, 1,3-cyc1opentadiene and 1,3-cyclohexadiene; carboxylic acids, such as 2,4-pentadienoic acid (beta-vinylacrylic acid) wrbic acid, muconic acid and eleostearic acid,

and the ester of such acids; halogenated hydrolike; and nitriles, such as I-cyano-IB-butadiene (beta-vinyl-acrylonitrile) and 2-cyano-1,3butadiene.- The ter olefinic double bond is meant to include any non-aromatic carbon-to-carbon double bond, whether occurring in an acyclic or in a cycloaliphatic system. Preferred compounds of this class are butadiene, isoprene, 2-ch1oro- 1,3-butadiene, 2bromo-1,3-butadiene and myrcene. Mixtures of two or pounds may be employed.

The dihalophosphine to be used in this process has th formula RPX2, in which R represents a member of the group consisting of alkyl, aryl and aralkyl radicals and X represents a member of the group consisting of chlorine and bromine. The preferred phosphines are phosphine and dichloroethylphosphine. A Wide variety of phosphine derivatives having the general formula shown may be employed. Representative compounds include those in which R represents an alkyl group such as methyl, ethyl, propyl, butyl or octyl; an aryl group such as phenyl or alphaor beta-naphthyl; or an aralkyl group such as benzyl or phenylethyl. In general, the lower members of these classes of radicals are most useful. These compounds ar readily available from several Well known procedures, such as by the action of a phosphorus trihalide on a hydrocarbon in on dialkyl or diaryl mercury. Kharasch in J. Org.

Chem. 14, 429 (1949) describes a process for making dichloroethylphosphine from phosphorus trichloride and lead tetraethyl. Th variou procedures for making these compounds are summarized in Kosolapolf, Organophosphorus 7Compounds, Wiley, N. Y. (1950), chapter 3.

The polymerization reaction is carried out with the aid of a free radical polymerization catalyst, such as an azonitrile, or a dialkyl or diacyl peroxide. The term free radical polymerization catalyst is also meant to include actinic radiation, and particularly ultraviolet light. The azonitrile catalysts which may be employed in this reaction are those set forth in detail in United States Patent No. 2,471,959 to Madison Hunt and include alpha, alpha'-azodiisobutyronitrile; alpha, alpha'-azobis-(alpha-methylbutyronitrile) alpha, alpha azobis (alphamethylisocapronitrile) and the like. Suitable peroxide catalysts include the dialkyl peroxides such as di-tert-butyl) peroxides, and the diacyl more of these com dichlorophenylthe presence of aluminum chlo-: ride, or by the action of a phosphorus trihalideperoxides such as butyryl, lauroyl and benzoyl peroxides. The amount of catalyst which may be used may vary over a wide range from 0.1% by weight upwards. From 1 to 5% by weight of oatalyst, based on the total weight of the monomeric reactants, is ordinarily desirable. The azonitriles represent the preferred class of catalysts.

The interpolymerization may b carried out at any temperature short of the decomposition point of the chemicals involved. The lower temperature limit is that at which the reaction becomes impractically slow. Temperature from to 125 C. may be used. The preferred range is from room temperature to about 75 C Within this range, no ceiling effect has been observed, i. e., there appears to be no temperature at which the rate of depolymerization balances or exceeds the rate of polymerization. The reaction will usually be carried out at atmospheric pressure, although higher or lower pres- .11 5 may e us d.-

Alt hough the intermediate interpolymer are most efficiently prepared by the use of polymerization catalysts of the type described, they may also be Prepared without the use of catalysts. Under such conditions, lower yields and lower de rees of polymerization are obtained. In my copending application Serial No. 240,807, a process is described in which conjugated dienes are reacted with substituted dihalophosphines under conditions calculated to give monomeric addition products. As there described, the reactions almost always yield some polymeric products in addition to the monomers.

In the formation of the intermediate interpolymer, the two reactants may be used in equimolecular amounts or an excess of one reactant or the other may be used to serve as a reaction medium. The amount of each reactant present is preferably between 5 and 95% by weight of the total amount of reactants. If the diene is present in excess, the composition of the interpolyxner' will ordinarily be affected to some extent, since the excess material can. take part in the polymerization. This is not true when the dihalo hosphin s pr sent in excess. Use of an excess. of diene results in increased yields of polymer and in the formati n of polymers havin increased viscosity. The reaction may be conducted in the presence of a non-reactive medium such as petroleum ether, cyclohexane, benzene, carbon tetrachloride, chloroform and the like. The mixture should be free of substancesv capable of converting the dihalo compounds. to. the corresponding oxides, such as water, alcohols and carboxylic acids.

When chloroform is used as the reaction medium, the polymerization proceeds with unusual rapidity and results polymers having higher viscosities than polymers obtained with the other common solvents. These polymers are also found to contain some chlorine, even after conversion of the dichlorotertiaryphosphine groups to phosphine oxide groups. Although the nature of this efiect' is not entirely understood, it appears that the chloroform in some way takes part in the polymerization reacti n, possibly by forming or aiding in the formation of cross-linkages or chain transfer.

The products of the polymerization, containing dihalotertiaryphosphine groups, are white to light brown; in color and vary in form from tacky togranular solids. The molecular weights of the polymers, measured by osmotic pressure after conversion, of the dihalotertiaryphosphine groups in increased yields of to phosphine oxide groups, are between 10,000 and 100,000. They contain varying amounts of phosphorus, since homopolymerization of the diene may take place at the same time and in competition with the interpolymerization. The extent to which the interpolymerization dominates is a function of the reactivities of the specific reagents under the particular reaction conditions. The phosphorus content of the interpolymer in most cases approaches the theoretical value for a polymer in which one mole of the diene has reacted with each mole of phosphine. This value varies with the molecular weight of the reagents. The theoretical maximum phosphorus content ofthe interpolymers, after conversionv to the phosphine oxides, is ordinarily from 10 to 20% by weight. Actually the interpolymer usually contains somewhat less phosphorus than the theoretical. The heat resistance and hydrophilic character of the polymers containing phosphine oxide groups increase in proportion to the amount of phosphorus present. As little as 0.1% phosphorus confers these properties on the polymer to a determinable extent, while at 2% phosphorus the effect is pronounced, Interpolymers containing from about 2 to 18%. phosphorus (after conversion to the phosphine oxide) represent the preferred class of products, made according to this invention.

Conversion of the dihalotertiaryphosphine group in the interpolymer to phosphine oxide. groups is produced by treatment of the inter mediate interpolymer with Water, an alcohol or a carboxylic acid. The general formula, of such compounds may be expressed as R'OI-l, where R. is hydrogen, a lower alkyl or a lower acyl radical. While water isv of course the cheapest member of this group and will often be chosen for this reason, use of alcohols or acids. affords. an opportunity to obtain valuable alkyl or acyl halides as by-products. The particular hydrolytic agent selected will depend on th economics of the situation and on the availability of materials. Methanol, ethanol, propanol, butanol,

formic acid, acetic acid, propionic acid and.

butyric acid are examples of compounds which may be used in place of water in this step.

The reaction to form the phosphine oxide groups is rapid andexothermic, and is operable at temperatures between 0 C. and well over and C. will 100 C. Operation between 0 usually be most convenient. Because of the exo-'- thermic nature of the reaction, complete control at the higher temperatures sometimes requires special cooling or dilution with an inert solvent. An excess of the hydrolytic agent may be used although it is only necessary to have at least a molar equivalent present in order to produce a complete conversion to the oxide.

The products of this invention are hard vitreous materials, varying in color from whitethrough yellow to tan. They are brittle and transparent. Most of them are soluble in methanol to the extent of at least 5%, and sometimes over 100%. They are very stable thermally, withstanding temperatures up to at least 300 C. The phosphine oxide groups are relatively inert chemically. The polymers are useful as fiameproofmg and antistatic agents for textiles and also in making molded articles and films. incorporated into other polymers to modify certain. properties. The hydrophilic, nature of the phosphine oxide groups increases the. ability of suchv polymers to absorb and to be wetted by hYd-roxyl-containing materials, making, the poly- They may be mers useful in diaphragms and other applications where this property is desired.

This invention is illustrated by the following examples.

Example 1 A mixture of 50.0 g. (0.28 m.) of redistilled dichlorophenylphosphine, 19.1 g. (0.28 m.) of redistilled isoprene containing no inhibitor and 700 mg. of alpha, alpha'-azobis-(alphamethylisocapronitrile) is warmed at about 40 C. for twentyfour hours. During this time a cream-colored solid gradually forms. A small amount of residual liquid is decanted, and the solid is washed with petroleum ether, then hydrolyzed with water to give a yellow-orange oil and the mixture is neutralized with sodium hydroxide. This oil is sepparated from the aqueous layer, washed with water and taken up in chloroform. Evaporation of the chloroform and drying of the residue at 90 C. mm.) gives 19.6 g. of a clear yellow-red vitreous resin.

Analysis.-Calcd. for Found: P=15.5%.

The product is therefore substantially the 1:1 heteropolymer, obtained in 37% conversion. By extraction of the acqueous hydrolysate layer with chloroform, followed by distillation, there is obtained an 18% yield of liquid monomeric adduct boiling at 160-165 C. (2 mm.).

Example 2 The procedure described in Example 1 is repeated to the point where the reaction mixture is hydrolyzed with water. The mixture is then salted and extracted with chloroform; The extract, which containsboth monomeric and polymeric products, is distilled. After removal of the chloroform, a 44% yield of distilled monomer and a 47% yield of a yellow glassy hard polymeric residue are obtained.

An identical run omitting the catalyst gives a 75.5% yield of distilled monomer and 7.5% yield of polymeric residue.

' Example 3 A mixture of 50 g. (0.28 m.) of dichlorophenylphosphine, 50 ml. of cyclohexane, 19.1 g. (0.28 m.) of redistilled isoprene and 0.7 g. of the catalyst of Example 1 is warmed at 40 C. for eighteen hours. The cream-colored solid is filtered, decomposed diluted with water and the in- C11H13OP: P=16.1

Example 4 dried at 100 C. for three days to give 11.6 g.

of a clear glassy brownish resin.

Example 5 'Using a 4: 1 mole ratio of reagents, a mixture of 88.2 g. (0.56 m.) of isoprene, 25.0 g. (0.14 m.) of dichlorophenylphosphine in 50 m1. of cyclohexane and 0.7 g. of the catalyst of Example 1 is warmed at40 C. for eighteen hours, during which time a The mixture is v an intrinsic viscosity of 0.27.

6 somewhat stringy white solid precipitates. .The mixture is filtered, hydrolyzed with water. washed and dried to give 18.4 g. of solid interpolymer containing 15.0% phosphorus (theory for the 1:1 adduct=16.l%).

Ewample 6 Example 7 A mixture of 46.2 g. (0.26 m.) of dichlorophenylphosphine, 18 g. (0.26 m.)' of isoprene, 0.5 g. of alpha, alpha azobis (alphamethylisocapronitrile) and ml.

The cream-colored solid which forms is filtered, treated with methanol to convert phosphorus dihalide groups to phosphine oxide groups, and diluted with water. The result- 2 ing polymer is dried to give 22 g. of resinous prod uct, having an intrinsic viscosity in methanol of 0.14. 1

This run is repeated under the same conditions except that 100 ml. of chloroform are used in place of the cyclohexane and the reaction is conducted for seventeen hours at 40 C. The product in this case weighs 47.5 g. and has an intrinsic viscosity in methanol of 0.40. It contains 4.9% chlorine (after treatment with methanol and water).

A third run is made using chloroform in place of the cyclohexane and time of three hours at 40 C. The polymeric product is obtained in a yield of 41.3 g. and has Example 8 Example 9 A mixture of 100.0- g. (0.56 m.) of dichlorophenylphosphine in 200 ml. of cyclohexane, 49.4 g. (0.56 m.) of 2-chlorobutadien'e-L3 and 0.50 g. of the catalyst of Example 1 is warmed at 45 C.

for two days and then at room temperature for three more days. The light brown solid which forms is treated by filtration, decomposition with methanol, and dilution with water to give an insoluble oil, which on drying gives 40 g. of reddish polymer.

Analysis.-Percent P=13.8; percent Cl=14.1.

Example 10 Warming a mixture of 50.0 g. (0.28 m.) of dichlorophenylphosphine in 100 ml. of cyclohexane, 34.4 g. (0.28m) of 2,3-dichloro-L3-butadiene and 1 g. of the catalyst of Example l-at 60C. for one day gives a tan solid product. This is worked up by filtration and digestion with hot of cyclohexane is warmed at 50 C. for twenty hours.

more methanol until there is no further evidence of reaction. Dilution with water and drying of the resultant solid at 100 0. gives 27.7 g. of a creamcolored solid.

Eazcmple 11- When a mixture of 50.0 g. (0.28 m.) of dichl'orophenylphosphine in 50 ml. of cyclohexane 18.5 g. (0.28 m.) of cyclopentadiene and 0.5 g. of the catalyst of Example 1 is warmed at C. for three days, ared brown solid slowly deposits. This solid is isolated by washing with petroleum ether, and is then decomposed with methanol and diluted with water to give about 1.2 g. of

solid (dry weight), containing 11.8% P.

Extraction with chloroform of. the aqueous layer from the decomposition and concentration gives a reddish-brown oil which on drying in vacuo at 100 C. gives 2.4 g. of a taining 14.4% P.

Example 12 Example 13 A mixture of 40.0 g. (0.305 m.) of dichloroethylphosphine in 50 ml. of cyclohexane, 20.8. g. (0.305 m.) of isoprene and 0.70 g. of the catalyst of Example 1 is warmed at C. for twenty hours. The white solid product is obtained by filtration of the reaction mixture. Hydrolysis of the solid. with water gives an aqueous solution. Saturation with salt, extraction with chloroform andconcentration gives 18.4 g. of a brown brittle glassy solid containing 18.0% P.

Example. 14

A mixture of 25.0 g. (0.19 m.) of dichloroethylphosphine in 50 ml. of cyclohexane, 25.41 g. (0.19 m.) at 2-bromo-1,3-butadiene and 0.5 g. of the catalyst of Example 1 is warmed at C. for twenty hours. A light tan solid polymer is formed. Filtration of the r action mass and hydrolysis with water gives a. heavy yellow oil which is separated from the aqueous layer and,

dried to give 21 g. of a yellow-brown resin containing 12.3% P and 48.0% Br.

Example 15 A. mixture. of 50.0 g. (0.28 m.) of dichlorophenylphosphine and ml. of cyclohexane, 19.1 g. (0.28 m.) of isoprene, 14.8 g. (0.28 m.) of acrylonitrile and. 0.50 g. of the catalyst of. Example 1. is warmed. at 40 C. for twenty hours. Filtration of the cream-colored solid polymer, con.- version of the dichlorotertiaryphosphineto. the corresponding phosphine oxide with. methanol and dilution with water gives an oil. This is separated, washed with water and dried to give 20.0 g. of a transparent brownish glass, containing 15.0% Pand 0.9% N.

Example 16 Theprocess described in Example 3 is repeated, using ultraviolet: light as: catalyst instead of the azonitrile catalyst.

viscous oil eon- This This gives 10.7 g. of poly-- mula ROH in meric dichlorophosphine. After conversion to the corresponding phosphine oxide. the. polymer contains 15.9% P.

When 500 mg. of dibenzoyl peroxide are used as catalyst in place oi the azonitrile or ultraviolet light, there are produced 2.0. g. of a polymeric phosphine oxide containing. 14.9% P.

In the. absence of. any polymerization catalyst, methanol-soluble interpolymers are obtainable by thev reaction between dichlo'rophenylphosphine and 1-cyano-l,3-butadiene, ethyl sorbate, l-(pnitrophenyl) 1,3 butadiene, 2 methoxy 1,3-- butadiene, and 1.-acetoxy-1,3-butadiene; and by' the reaction between. dichloronaphthylphosphine and isoprene.

I claim:

1. In a process. for preparing a. heat-resistant polymeric addition product containing chemically bound. phosphorus in the form of. phosphine oxide. groups, the step which comprises contacting a phosphorus-containing polymeric addition product of: apolymerizable organic compound containing coniugated olciinic double bonds and a mono-substituted dihalophosphine having the formula RPXz, in which R. represents a member of the group consisting of allzyl, aryl and. aralkyl. radicals and X is a member of the group consisting of chlorine and'bromine, with a hydroxyl-containing compound having the forwhich R represents a member of the group consisting of hydrogen, lower alkyl and lower acylradicals.

2. A process according to claim 1 in which the polymerizable: organic compound is selected from the group consisting of butadiene, isoprene, 2-ch1oro-L3-butadiene and 2-bromo-1,3-butadiene.

3. A heat-resistant polymeric addition product containing at least 0.1% chemically bound. phosphorus in the form of phosphine oxide. groups. said addition product being prepared by .the reaction of a hydroxyl-containing compound having the formula ROH in which R represents a member of the group consisting of hydrogen,

' lower alkyl and lower acyl radicals with a polymeric addition product. of a polymerizabie organic compound containing conjugated oleiinic double. bonds and a mono-substituted dihal'ophosphine having the formula RPXZ in which R represents a member of the. group consisting of alkyl, aryl and aralkyliradicals and X is a member of the group consisting of chlorine and bromine.

4. The polymeric addition product of claim 3' in which the polymerizable organic compound is selected from the group consisting of butadiene, isoprenc, 2-chloro-1,3-butadiene and 2-bromo- 1,3-butadiene.

5. The polymeric addition product ofclaim 3- in which the polymerizable organic compound is butadiene.

6-. The polymeric addition product of claim- 3 in which the polymerizable organic compound is isoprene.

7. The" polymeric addition product ofclaim 3 inwhich the polymerizable organic compound is 2'-chloro-1,3-butadiene.

8. A process according to claim 1 in which the polymerizableorganic compound is butadiene.

9. A process according to claim 1 in which the polymerizable organic compound is isoprene.

10. A process according to claim 1 in which the polymerizable organic compound is 2chloro- 1,3-butadiene.

11. In a process'for preparing aheat-resistant phine with methanol.

12. In a process for preparing a heat-resistant polymeric addition product containing chemically bound phosphorus in the form of phosphine oxide groups, the step which comprises contacting a phosphorus-containing polymeric addition product of isoprene and diohlorophenylphosphine with methanol.

13. In a process for preparing a heat-resistant polymeric addition product containing chemically bound oxide groups, the ste phosphorus in the form of phosphine p which comprises contacting a phosphorus-containing polymeric addition product of 2-ch1oro- 5 phenylphosphine with 14. A process ace the hydroxyl- Number methanol.

1,3-butadiene and dichloroording to claim 1 in which containing compound is water.

WILLIAM B. MCCORMACK.

UNITED STATES PATENTS Date Aug. 14, 1945 Aug. 29, 1950 

1. IN A PROCESS FOR PREPARING A HEAT-RESISTANT POLYMERIC ADDITION PRODUCT CONTAINING CHEMICALLY BOUND PHOSPHORUS IN THE FORM OF PHOSPHINE OXIDE GROUPS, THE STEP WHICH COMPRISES CONTACTING A PHOSPHORUS-CONTAINING POLYMERIC ADDITION PRODUCT OF A POLYMERIZABLE ORGANIC COMPOUND CONTAINING CONJUGATED OLEFINIC DOUBLE BONDS AND A MONO-SUBSTITUTED DIHALOPHOSPHINE HAVING THE FORMULA RPX2, IN WHICH R REPRESENTS A MEMBER OF THE GROUP CONSISTING OF ALKYL, ARYL AND ARALKYL RADICALS AND X IS A MEMBER OF THE GROUP CONSISTING OF CHLORINE AND BROMINE, WITH A HYDROXYL-CONTAINING COMPOUND HAVING THE FORMULA R''OH IN WHICH R'' REPRESENTS A MEMBER OF THE GROUP CONSISTING OF HYDROGEN, LOWER ALKYL AND LOWER ACYL RADICALS. 